Slew rate is the maximum rate of change of output voltage with respect to time. Specified in V/μs.

**Slew Rate**

Slew
rate is the maximum rate of change of output voltage with respect to time.
Specified in V/μs.

There
is usually a capacitor within 0, outside an op-amp oscillation. It is this
capacitor which prevents the o/p voltage from fast changing input. The rate at
which the volt across the capacitor increases is given by

dVc/dt
= I/C --------(1)

I
-> Maximum amount furnished by the op-amp to capacitor C.

Op-amp
should have the either a higher current or small compensating capacitors.

For
741 IC, the maximum internal capacitor charging current is limited to about
15μA. So the slew

rate
of 741 IC is

SR
= dVc/dt |max = I_{max}/C

For
a sine wave input, the effect of slew rate can be calculated as consider volt
follower. The input is large amp, high frequency sine wave.

If
V_{s} =V_{m} Sinwt then output V0 = Vm sinwt .

The
rate of change of output is given by dV0/dt=Vm w coswt.

The max rate of change of output across
when coswt =1

(i.e)
SR =dV0/dt |max = wVm.

SR = 2 fVm V/s = 2fVm v/ms.

Thus
the maximum frequency fmax at which undistorted output volt of peak value Vm is
given by fmax (Hz) = Slew rate/6.28 * Vm called the full power response. It is
maximum frequency of a large amplitude sine wave with which op-amp can have
without distortion.

Tags : Operational Amplifiers , Linear Integrated Circuits : Basics of Operational Amplifiers

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Linear Integrated Circuits : Basics of Operational Amplifiers : Slew Rate | Operational Amplifiers

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